Quantized Precoded Spatial Multiplexing and STBC Systems
Spatial multiplexing is a common space-time modulation technique for MIMO systems capable of transmitting multiple independent data streams providing substantial capacity and diversity. Unfortunately spatial multiplexing is sensitive to ill-conditioning of the channel matrix. Precoding is a method of using a linear transformation of the symbols at the transmitter that improves the resilience of spatial multiplexing at the expense of channel knowledge. In a limited feedback scenario, the transmitter is provided with a quantized precoded matrix and most of the gains of a precoded spatial multiplexing system can be achieved at the cost of a few bits of feedback. Orthogonal space time block codes (OSTBCs) are a class of easily decoded space-time codes that achieve full diversity order in Rayleigh fading channels. OSTBCs exist only for certain numbers of transmit antennas and so not provide array gain like diversity techniques that exploit transmit channel information. When channel state information is available at the transmitter, precoding the space-time codeword can be used to support different numbers of transmit antennas and improve array gain. The limited feedback approach provides the transmitter with a quantized precoding matrix and can derive most of the gains of a precoded OSTBC system. Our constributions include proposing codebook design criteria for quantized precoded spatial multiplexing and OSTBC systems, analyzing the performance of such systems and demonstrating the gains achievable using specific codebook constructions.
Related Publications and Preprints:
[1] D. J. Love and R. W. Heath, Jr., ``Diversity Performance of Precoded Orthogonal Space-Time Block Codes Using Limited Feedback'','' IEEE Communication Letters, vol. 8, pp. 305-307, May 2004.
[2] D. J. Love and R. W. Heath, Jr., ``Limited feedback unitary precoding for orthogonal space-time block codes,'' IEEE Trans. on Signal Processing, vol. 53, no. 1, pp. 64-73, January 2005.
[3] D. J. Love and R. W. Heath, Jr., ``Limited Feedback Unitary Precoding for Spatial Multiplexing,'' IEEE Trans. on Info. Theory, vol. 51, no. 8, pp. 2967 - 2976, August 2005.
[4] D. J. Love and R. W. Heath, Jr., ``Grassmannian Precoding for Spatial Multiplexing Systems,'' Proc. of the Allerton Conf. on Comm. Control and Comp., pp. 356-357, Monticello, IL, Oct. 1 - 3, 2003.
[5] D. J. Love and R. W. Heath, Jr., ``Limited Feedback Precoding for Spatial Multiplexing Systems using Linear Receivers'' Proc. of the Military Communications Conference, vol. 1, pp. 627 - 632, Boston, MA, Oct. 13-16, 2003.
[6] D. J. Love and R. W. Heath, Jr., ``Limited Feedback Precoding for Spatial Multiplexing Systems,'' Proc. of the IEEE Global Telecommunications Conf. , vol. 4, pp. 1857-1861, San Francisco, CA, Dec. 1-5, 2003.
[7] D. J. Love and R. W. Heath, Jr., ``Limited Feedback Precoding for Orthogonal Space-Time Block Codes,'' Proc. of the IEEE Global Telecommunications Conf. , vol. 1, pp. 561-565, Dallas, TX, Nov. 29 - Dec. 3, 2004.
